Task:

Perform network address translation on a client router and advertise the natted address into a routing protocol, so that it will show up in the connecting network’s routing table. Do not enable the routing protocol on the client network and don’t use the redistribute static command.

Solution:

!
! Advertise this loopback into a routing protocol
!
interface Loopback0
 description Loopback used for Nat
 ip address 192.168.120.50 255.255.255.255
!
! Local Client Network that needs to be natted
!
interface FastEthernet0
 description Customer Local Lan
 ip address 10.0.1.1 255.255.255.0
 ! This command goes on the network to be natted
 ip nat inside
!
!
interface Serial0
 encapsulation frame-relay IETF
!
! WAN sub-interface that connects lan to trusted network
!
interface Serial0.1 point-to-point
 description Wan PVC to Corporate Network
 ip address 172.31.1.2 255.255.255.252
 frame-relay interface-dlci 101
 ! This command goes on the interface that traffic will leave on
 ip nat outside
!
router eigrp 110
 !Enable EIGRP on Wan interface
 network 172.31.1.2 0.0.0.0
 !Put loopback into routing protcol, thus advertising it.
 network 192.168.120.50 0.0.0.0
 no auto-summary
!
! Nat everthing coming in on the interface marked ‘inside’ that
! matches access list 1 to the IP address assigned to Loopback0.
! Use the overload keyword to perform (one to many) Port address translation
ip nat inside source list 1 interface Loopback0 overload
!
! List of IP’s that need to be natted to Loopback0’s IP address
access-list 1 remark Hosts to Nat
access-list 1 permit 10.0.1.0 0.0.0.255